Transformer Condition Control: Advanced and Traditional Technologies

Description

This book is devoted to one of the main problems of modern electrical power engineering—power transformer diagnostics. The first three chapters discuss the fundamentals: The first chapter presents the physical reasons for power transformers’ failures and the technical and economic consequences of disruption of the normal operation. The second chapter reviews the standard technologies for monitoring the state of the high-voltage transformers. The third chapter tells about monitoring the condition of transformer windings based on the pulse method. The fourth chapter presents the technologies for transformer windings condition controlled by means of nanosecond pulses. The stages of improving the pulsed method based on a short probing pulse of the nanosecond range, the results of experiments on identifying the radial and axial displacements of the winding, studies of the effect of the duration and shape of the probing pulse on the sensitivity of the diagnostic procedure, and the stages of developing a mathematical as well as physical model of a power transformer are consistently presented. Preface About This Book Contents 1 Causes of Power Transformer Failure 1.1 Failure Statistics of Transformer Construction Elements 1.2 Technical and Economic Consequences of Failures in Standard Operation of Transformers 1.3 Insulation Aging (Degradation) 1.4 Integrity Violation of Transformer Windings References 2 Standardized Technologies of Condition Monitoring for High Voltage 2.1 Non-electrical Control Methods 2.1.1 Physicochemical Control Methods 2.1.2 Vibration Control 2.2 Electrical Control Methods 2.2.1 Insulation Condition Monitoring by PD Registration 2.2.2 Idling Loss Measurement 2.2.3 Transformation Ratio Measurement 2.2.4 Insulation Resistance Monitoring for Transformer Windings 2.2.5 Measurement of Winding DC-Resistance 2.2.6 Short-Circuit Resistance Monitoring References 3 Diagnostics of Transformer Windings Condition by Probing Pulses of Microsecond Duration 3.1 Physical Basis and Development of Pulsed Diagnostics 3.2 Development of Pulsed Diagnostics Technology 3.3 Frequency Analysis as a Development of Pulsed Diagnostics References 4 Probing Transformer Windings with Nanosecond Pulses 4.1 Physical Prerequisites for Increasing the Efficiency of PD Technology by Reducing the Duration of Probe Pulses 4.2 Elaboration of ID Technology on Physical and Mathematical Models of a Power Transformer 4.2.1 Creating a Physical Model of a Power Transformer 4.2.2 Detection of Turn-to-Turn Short Circuits 4.2.3 Passage of Probe Pulses Through the Windings of the Physical Model of a Transformer 4.2.4 Detection of Radial and Axial Displacements of Winding Turns 4.2.5 Regularities of Response Formation for Various Methods of Connecting the Windings 4.2.6 Possibilities of Diagnostic Procedures Under Operating Voltage: Experimental Research 4.2.7 Influence of Probe Pulse Parameters on Diagnostic Sensitivity Investigated 4.2.8 Research of a Power Transformer Using a Mathematical Model 4.3 Diagnostic Complex Implementing the PD Technology in Nanosecond Mode 4.3.1 Object Description and Experimental Procedure 4.3.2 Choice of Efficiency Criterion 4.4 Effectiveness Comparison for the FRA and PD Technologies 4.4.1 Diagnostics by Nanosecond Pulses 4.4.2 Diagnostics Using FRAX-150 4.4.3 Diagnostics of “Axial Displacement of Turns” Defetcs in the HV Winding of Phase a by Probing with Nanosecond Pulses 4.4.4 Diagnostics of “Axial Displacement of Turns” Defects in the HV Winding of Phase a by FRA Method Using FRAX-150 Device 4.5 Technology of Single-Stage Pulsed Defectography 4.5.1 Winding Condition Monitoring While Using a Single Stage 4.5.2 Implementation of Single-Stage Defectography 4.5.3 Comparison of Spectra for Pulses Applied to Defect-Free Windings 4.6 ON-LINE Monitoring of Winding Conditions References 5 Development of a Schematic Diagram and a Probing Pulsed Generator Prototype References 6 Single-Stage Defectography of Windings with Various Defect Degree Development 6.1 Displacement (Lodging) of Four Turns in the HV Winding of Phase a (Defect No. 1) 6.2 Displacement (Lodging) of 8 Turns of the HV Winding of Phase a (Defect No. 2) References Conclusion